The present disclosure relates to digital images.
Image capture devices, e.g., cameras, can be used to capture an image of a section a field of view. Additionally, such image capture devices can have varying fields of view. The field of view captured by a particular camera depends in part on a focal length of the camera lens and a film size. A wide-angle lens has a focal length that is smaller than a normal lens (e.g., a lens having a focal length substantially equal to a diagonal length of the film size). For a constant film size, a wide angle lens captures a larger field of view relative to a lens with a larger focal length.
Any image captured by an input device often includes some distortions. For example, a camera can distort the sizes of objects depicted in the image so that distant objects appear smaller than closer objects. In particular, capturing an image results in a projection of the section of the view. This projection can vary depending on the viewpoint of the image capture device, which results in perspective distortion between the captured images.
Some wide-angle images provide rectilinear images having a large field of view (e.g., a 24 mm wide-angle lens for a 35 mm camera). Other wide-angle lenses do not provide a rectangular image, for example, some fisheye lenses. A fisheye lens provides a wide angle hemispherical image, which can be cropped to a traditional rectangular image.
Additionally, wide-angle lenses intrinsically generate additional distortions, particularly near the edges where, for example, lines that appear straight in the real world appear bent and circles stretch into ovals.
Another form of wide-angle image is a composite image (e.g., a panoramic image) formed from stitching together two or more component images. Thus, to generate an image of the larger view, multiple overlapping images of sections of views can be taken, and the images can be stitched together to form a composite image. The composite image can also include distortions including perspective distortions.